Multifrequency observations of the cometary nebula P18 (NGC 2316).

Multifrequency observations have been obtained for the cometary nebula P18 (NGC 2316). The set of data consists of CCD frames in the I and R bands; J,H,K and Larcmin near-infrared photometry and maps in the H and K bands, and radio continuum observations at λ 6-cm. These have been combined with previously published photometry at 10 and 22 μm, IRAS and Kuiper data. The results indicate that P18 is a compact H II region located at a distance of ≡1 kpc and is being excited by an embedded single early B-type star. Two condensations located near the apex of the nebula, apparent in the optical-red and near-infrared maps and previously misidentified as "stars", are related to light from the H II region shining through the disrupted circumstellar dust shell.